1 /* getroot.c: get the root dentry for an NFS mount 2 * 3 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/module.h> 13 #include <linux/init.h> 14 15 #include <linux/time.h> 16 #include <linux/kernel.h> 17 #include <linux/mm.h> 18 #include <linux/string.h> 19 #include <linux/stat.h> 20 #include <linux/errno.h> 21 #include <linux/unistd.h> 22 #include <linux/sunrpc/clnt.h> 23 #include <linux/sunrpc/stats.h> 24 #include <linux/nfs_fs.h> 25 #include <linux/nfs_mount.h> 26 #include <linux/nfs4_mount.h> 27 #include <linux/lockd/bind.h> 28 #include <linux/smp_lock.h> 29 #include <linux/seq_file.h> 30 #include <linux/mount.h> 31 #include <linux/nfs_idmap.h> 32 #include <linux/vfs.h> 33 #include <linux/namei.h> 34 #include <linux/mnt_namespace.h> 35 #include <linux/security.h> 36 37 #include <asm/system.h> 38 #include <asm/uaccess.h> 39 40 #include "nfs4_fs.h" 41 #include "delegation.h" 42 #include "internal.h" 43 44 #define NFSDBG_FACILITY NFSDBG_CLIENT 45 #define NFS_PARANOIA 1 46 47 /* 48 * get an NFS2/NFS3 root dentry from the root filehandle 49 */ 50 struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) 51 { 52 struct nfs_server *server = NFS_SB(sb); 53 struct nfs_fsinfo fsinfo; 54 struct nfs_fattr fattr; 55 struct dentry *mntroot; 56 struct inode *inode; 57 int error; 58 59 /* create a dummy root dentry with dummy inode for this superblock */ 60 if (!sb->s_root) { 61 struct nfs_fh dummyfh; 62 struct dentry *root; 63 struct inode *iroot; 64 65 memset(&dummyfh, 0, sizeof(dummyfh)); 66 memset(&fattr, 0, sizeof(fattr)); 67 nfs_fattr_init(&fattr); 68 fattr.valid = NFS_ATTR_FATTR; 69 fattr.type = NFDIR; 70 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR; 71 fattr.nlink = 2; 72 73 iroot = nfs_fhget(sb, &dummyfh, &fattr); 74 if (IS_ERR(iroot)) 75 return ERR_PTR(PTR_ERR(iroot)); 76 77 root = d_alloc_root(iroot); 78 if (!root) { 79 iput(iroot); 80 return ERR_PTR(-ENOMEM); 81 } 82 83 sb->s_root = root; 84 } 85 86 /* get the actual root for this mount */ 87 fsinfo.fattr = &fattr; 88 89 error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 90 if (error < 0) { 91 dprintk("nfs_get_root: getattr error = %d\n", -error); 92 return ERR_PTR(error); 93 } 94 95 inode = nfs_fhget(sb, mntfh, fsinfo.fattr); 96 if (IS_ERR(inode)) { 97 dprintk("nfs_get_root: get root inode failed\n"); 98 return ERR_PTR(PTR_ERR(inode)); 99 } 100 101 /* root dentries normally start off anonymous and get spliced in later 102 * if the dentry tree reaches them; however if the dentry already 103 * exists, we'll pick it up at this point and use it as the root 104 */ 105 mntroot = d_alloc_anon(inode); 106 if (!mntroot) { 107 iput(inode); 108 dprintk("nfs_get_root: get root dentry failed\n"); 109 return ERR_PTR(-ENOMEM); 110 } 111 112 security_d_instantiate(mntroot, inode); 113 114 if (!mntroot->d_op) 115 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 116 117 return mntroot; 118 } 119 120 #ifdef CONFIG_NFS_V4 121 122 /* 123 * Do a simple pathwalk from the root FH of the server to the nominated target 124 * of the mountpoint 125 * - give error on symlinks 126 * - give error on ".." occurring in the path 127 * - follow traversals 128 */ 129 int nfs4_path_walk(struct nfs_server *server, 130 struct nfs_fh *mntfh, 131 const char *path) 132 { 133 struct nfs_fsinfo fsinfo; 134 struct nfs_fattr fattr; 135 struct nfs_fh lastfh; 136 struct qstr name; 137 int ret; 138 139 dprintk("--> nfs4_path_walk(,,%s)\n", path); 140 141 fsinfo.fattr = &fattr; 142 nfs_fattr_init(&fattr); 143 144 /* Eat leading slashes */ 145 while (*path == '/') 146 path++; 147 148 /* Start by getting the root filehandle from the server */ 149 ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 150 if (ret < 0) { 151 dprintk("nfs4_get_root: getroot error = %d\n", -ret); 152 return ret; 153 } 154 155 if (fattr.type != NFDIR) { 156 printk(KERN_ERR "nfs4_get_root:" 157 " getroot encountered non-directory\n"); 158 return -ENOTDIR; 159 } 160 161 /* FIXME: It is quite valid for the server to return a referral here */ 162 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { 163 printk(KERN_ERR "nfs4_get_root:" 164 " getroot obtained referral\n"); 165 return -EREMOTE; 166 } 167 168 next_component: 169 dprintk("Next: %s\n", path); 170 171 /* extract the next bit of the path */ 172 if (!*path) 173 goto path_walk_complete; 174 175 name.name = path; 176 while (*path && *path != '/') 177 path++; 178 name.len = path - (const char *) name.name; 179 180 eat_dot_dir: 181 while (*path == '/') 182 path++; 183 184 if (path[0] == '.' && (path[1] == '/' || !path[1])) { 185 path += 2; 186 goto eat_dot_dir; 187 } 188 189 /* FIXME: Why shouldn't the user be able to use ".." in the path? */ 190 if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2]) 191 ) { 192 printk(KERN_ERR "nfs4_get_root:" 193 " Mount path contains reference to \"..\"\n"); 194 return -EINVAL; 195 } 196 197 /* lookup the next FH in the sequence */ 198 memcpy(&lastfh, mntfh, sizeof(lastfh)); 199 200 dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path); 201 202 ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name, 203 mntfh, &fattr); 204 if (ret < 0) { 205 dprintk("nfs4_get_root: getroot error = %d\n", -ret); 206 return ret; 207 } 208 209 if (fattr.type != NFDIR) { 210 printk(KERN_ERR "nfs4_get_root:" 211 " lookupfh encountered non-directory\n"); 212 return -ENOTDIR; 213 } 214 215 /* FIXME: Referrals are quite valid here too */ 216 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) { 217 printk(KERN_ERR "nfs4_get_root:" 218 " lookupfh obtained referral\n"); 219 return -EREMOTE; 220 } 221 222 goto next_component; 223 224 path_walk_complete: 225 memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid)); 226 dprintk("<-- nfs4_path_walk() = 0\n"); 227 return 0; 228 } 229 230 /* 231 * get an NFS4 root dentry from the root filehandle 232 */ 233 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 234 { 235 struct nfs_server *server = NFS_SB(sb); 236 struct nfs_fattr fattr; 237 struct dentry *mntroot; 238 struct inode *inode; 239 int error; 240 241 dprintk("--> nfs4_get_root()\n"); 242 243 /* create a dummy root dentry with dummy inode for this superblock */ 244 if (!sb->s_root) { 245 struct nfs_fh dummyfh; 246 struct dentry *root; 247 struct inode *iroot; 248 249 memset(&dummyfh, 0, sizeof(dummyfh)); 250 memset(&fattr, 0, sizeof(fattr)); 251 nfs_fattr_init(&fattr); 252 fattr.valid = NFS_ATTR_FATTR; 253 fattr.type = NFDIR; 254 fattr.mode = S_IFDIR | S_IRUSR | S_IWUSR; 255 fattr.nlink = 2; 256 257 iroot = nfs_fhget(sb, &dummyfh, &fattr); 258 if (IS_ERR(iroot)) 259 return ERR_PTR(PTR_ERR(iroot)); 260 261 root = d_alloc_root(iroot); 262 if (!root) { 263 iput(iroot); 264 return ERR_PTR(-ENOMEM); 265 } 266 267 sb->s_root = root; 268 } 269 270 /* get the info about the server and filesystem */ 271 error = nfs4_server_capabilities(server, mntfh); 272 if (error < 0) { 273 dprintk("nfs_get_root: getcaps error = %d\n", 274 -error); 275 return ERR_PTR(error); 276 } 277 278 /* get the actual root for this mount */ 279 error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr); 280 if (error < 0) { 281 dprintk("nfs_get_root: getattr error = %d\n", -error); 282 return ERR_PTR(error); 283 } 284 285 inode = nfs_fhget(sb, mntfh, &fattr); 286 if (IS_ERR(inode)) { 287 dprintk("nfs_get_root: get root inode failed\n"); 288 return ERR_PTR(PTR_ERR(inode)); 289 } 290 291 /* root dentries normally start off anonymous and get spliced in later 292 * if the dentry tree reaches them; however if the dentry already 293 * exists, we'll pick it up at this point and use it as the root 294 */ 295 mntroot = d_alloc_anon(inode); 296 if (!mntroot) { 297 iput(inode); 298 dprintk("nfs_get_root: get root dentry failed\n"); 299 return ERR_PTR(-ENOMEM); 300 } 301 302 security_d_instantiate(mntroot, inode); 303 304 if (!mntroot->d_op) 305 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 306 307 dprintk("<-- nfs4_get_root()\n"); 308 return mntroot; 309 } 310 311 #endif /* CONFIG_NFS_V4 */ 312